Egypt's most dangerous terrorist group IS-affiliated Wilayat Sinai, has been named as the key suspect behind the downing of Metrojet Flight 9268.

The so-called ‘Islamic State's province in the Sinai’, formerly known as Ansar Bayt al-Maqdis swore allegiance to ISIS leader Abu Bakr al-Baghdadi last year, but have killed scores of Egyptian army personnel, politicians and civilians in a horrific terror campaign of suicide bombers, car bombs and roadside IEDs since 2011.

And it would not be the first time the militants downed a flight - having shot down an Egyptian military helicopter in January 2014 with a surface-to-air missile, killing all five people on board.

British tourists were warned of a ‘high threat’ from terrorism in Egypt after the group claimed a missile attack on a naval patrol ship off the coast of Sinai in July earlier this year.

Dangerous: A militant with Ansar Bayt al-Maqdisi, later renamed Wilayat Sinai shoots down an Egyptian military helicopter in the Sinai in January 2014

Split: Some factions of the group, also known as Ansar Bayt al-Maqdisi, which translates as Supporters of Jerusalem, are thought to be loyal to Al-Qaeda

Bombs: Egypt security forces have been fighting militants for years in concerted counter-terror efforts. They face frequent bombings of police stations and attacks on military bases. Officials suspect the group have inside army informants given the accuracy and timings of attacks

Also known as Ansar Bayt al-Maqdis, the Salafist Sunni group originally declared themselves Al Qaeda's wing in the Sinai in 2011, although they were never formally accepted by top terror chiefs.

Fighting in a convoluted battleground where numerous jihadist groups vie for power, claiming the worst aviation terror attack since 9/11 will greatly boost their cause.

Previously it is thought only a faction of the group have wholeheartedly embraced IS, with others still with one foot in the Al Qaeda camp as the two global extremist organisations fight for influence.

Their exact size is unknown, but estimates say they have between hundred and a few thousand fighters.

According to TRAC, the Terrorism research and Analysis Consortium, they are mostly composed of local Bedouins, but also recruits members from Egypt and beyond.

Violent: Islamic extremists have continued to target Egyptian security forces in the Sinai peninsula. Above, the aftermath of the bombing of a police station in el-Arish, northern Sinai in April 2015

In the weeks after ISIS released the brutal beheading of US journalist James Foley in August 2014, the group posted a similar style video of the beheading of four Egyptian citizens in the Sinai desert, who they accused of being 'Israeli spies'.

Major Attacks

January 2014: Downed a Egyptian military helicopter in the Sinai with a missile launcher, killed 5

January 2014: Series of bomb attacks across Cairo, killed 6, wounded 70+

February 2014: Attacked tourist bus in Sinai, killed 4

August 2014: Released execution video of four Egyptian citizens

July 2015: Claimed missile on Egyptian naval patrol boat off the coast of the Sinai

Egyptian forces have been attempting a crackdown, but say they fear the group have numerous military informants with inside information on army deployments.

While originally focused on targeting Israel, the group changed tack after the removal of Muslim Brotherhood backed Egyptian President Morsi.

They have also been accused of attacking Palestinian Hamas convoys in the Gaza Strip, and recruiting jihadists to fight with ISIS in Iraq and Syria.

Capitalising on an increasingly lawless region, militants are thought to be receiving resources and refuge on both side of the Nile - from Gaza in the east and Libya to the west.

The suspicion that they were using supply tunnels into the Gaza Strip (used to evade the Israeli blockade) is reportedly what led to the Egyptian crackdown in Rafa, on the Gazan/Egyptian border in summer 2013.

The Egyptian security forces claim to have killed at least two of their top leadership, with a third death disputed by the group.

Still alive is top commander Ahmed Salam Mabruk, Egyptian officials suggest has been a senior leader of Ansar Jerusalem since his release from prison in 2012. He has strong ties to Al Qaeda and was a member of al-Gama’s al-Islamiya, an active Egyptian extremist group in the 1990s.

Explosion: Extremists loyal to ISIS in Egypt attacked a naval patrol ship in off the coast of Sinai causing it to burst into flames in July 2015

Attack: Eyewitnesses said a boat patrolling the Sinai coastline spotted a group of ISIS jihadis on the shore and engaged them. A rocket fired from the shore (circled) struck the vessel moments later